Elevating mechanism for dental chairs and the like

ABSTRACT

Disclosed is an elevating mechanism for dental chairs and the like wherein the chair is supported on one end of a cantilevered arm which is pivoted through a vertical arc to raise and lower the chair. Motion control means operating on a extension of the cantilevered arm acts to translate the arm horizontally as it is pivoted to an upright position so that the net result is that the chair travels vertically through a substantially rectilinear path of travel instead of a arcuate path of travel.

United States Patent [191 Wilson et al.

[111 3,807,680 [451 Apr. 30, 1974 Joseph Finsterwalder, both of Rochester, NY.

Assignee: Sybron Corporation, Rochester,

Filed: Sept. 14, 1972 Appl. No.: 288,897

[52] US. Cl. 248/421 [51] Int. Cl. A47c 1/04 [58] Field of Search 248/421, 404; 297/345; 74/ 103, 105

[56] References Cited UNITED STATES PATENTS 521,256 6/1894 Browne 248/421 3,083,055 3/1963 Davis 297/345 3,484,004 12/1969 Hughey... 74/103 3,698,673 10/1972 Olsen 248/421 Primary ExaminerMarion Parsons, Jr. Attorney, Agent, or FirmTheodore B. Roessel; Roger Aceto 5 7 ABSTRACT Disclosed is an elevating mechanism for dental chairs and the like wherein the chair is supported on one end of a cantilevered arm which is pivoted through a vertical arc to raise and lower the chair. Motion control means operating on a extension of the cantilevered arm acts to translate the arm horizontally as it is pivoted to an upright position so that the net result is that the chair travels vertically through a substantially rectilinear path of travel instead of a arcuate path of travel.

2 Claims, 2 Drawing Figures PATENTEDAPR 30 m4 ,SHEEI 1 OF 2 ELEVATING MECHANISM FOR DENTAL CHAIRS AND THE LIKE BACKGROUND OF THE INVENTION The present invention relates generally to a cantilevered lift machanism for dental chiars and the like and more particularly to such a lift machanism which is capable of moving the chair substantially vertically instead of through an arcuate path of travel.

Cantilevered lift machanisms for dental chairs and the like are well known in the art and are shown for example, in US. Pat. Nos. 3,083,055 and 3,544,498. The main advantage of a cantilever lift is that the low to high range of motion is relatively large. Generally, chairs with cantilevered lifts have a low limit of travel, higher than conventional dental chair lifts, and a high limit of travel, higher than conventional dental chair lifts. This is because a cantilevered arm can be arranged to lie along the floor surface on the one hand and then can be pivoted to a vertical or near vertical position on the other hand, the high position being limited only by the length of the arm.

The main disadvantage of a cantilever-type lift is the relatively large amount of horizontal translation that occurs as the chair is moved in an are between its low and high positions. Such translation is undesired because it requires the dentist to reorient his instrumentation each time the patient is raised or lowered. Several schemes have been developed -to compensate for this horizontal translation. One scheme is to use a double cantilever wherein one moves the chair up and forward and the second cantilever moves the chair up and rearward. Still another scheme is to have a tilt mechanism which tilts the chair rearward as the cantilever lifts the chair upward and forward. Still another, simpler, scheme is to have the supported end of the cantilever arm located higher than the outward extending end of the arm when the chair is in the low position. The working range of the arm is then limited to the relatively flat portion of the are described by the outward extending end as it moves up to and then above the level of the supported end. Such anarrangement, while it does reduce the amount of horizontal'translation of the chair during lifting, restricts the range of the height adjustment.

In the present invention, horizontal displacement of the chair as the cantilevered arm is pivoted to an up-.

SUMMARY OF THE INVENTION The present invention may be characterized in one aspect thereof by the provision of a base member adapted to'rest on a floor surface and having an upstanding forward portion; a support link pivoted to the upstanding portion for arcuate movemement in a vertical plane; a cantilevered arm pivoted intermediate its end to the link, the outward extending end of the arm supporting a dental chair or the like; drive means acting between the support link and the base for moving the link and therefore the cantilevered arm in an arcuate path about the upstanding base portion; a motion compensator connected to the base and to an end of the cantilevered arm on the far side of the link form the unsupported end, the compensator acting to convert the normal rotating motion of the unsupported end to nearly a straight line motion; and parallelogram means between the base and the dental chair for maintaining the chair substantially horizontal as it is elevated.

DESCRIPTION OF THE DRAWING DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, FIG. 1 shows the elevating mechanism of the present invention generally indicated at 10 supporting a dental chair or the like. The seat portion of the chair is shown at 12. While the present invention is being described in connection with a dental chiar, it should be appreciated that it may be used in connection with any other patient support, such a podiatry chair, surgical table, examination table or the like.

. The elevating mechanism includes a base portion 14 which has two spaced upstanding side members 16 and 18 and an upstanding'c'entral member 20. Side members 16 and 18 support the elevating linkages described herein below while the upstanding central portion 20 provides an anchor point for the motor means to elevate the chair. It should be understood that while there is a set of elevating linkages carried by each of the upstanding side members 16 and 18, the two sets are identical so that only the linkages connected to upstanding side member 16 will be described in detail.

The elevating linkage includes a lifting arm 22 which supports the dental chair in cantilever fashion outwardly spaced from base 14. In this respect the outwardlyextending end 24 of the arm is pivoted to a knuckle 26, which in turn is attached to the seat 12 of the dental chair. The other end- 28 of the lifting arm is journaled at 30 to one end of a motion compensating link 32. Link 32 has its other end 34 keyed to a shaft 36 which isjournaled to and extends between upstanding side members 16 and 18.

Lifting arm 22 is also journaled to a pin 38 carried by one end of a support link 40. It 'should be appreciated that pin 38 is intermediate the ends of lifting arm 22 but is closer to end 28 so that the cantilever length from pin 38 to end 24 is substantially greater than the distance between pin 38 and 28.

As shown in FIG. 1, support link 40 has its other end.

keyed to a shaft 42 located above and forward of shaft 36. This shaft is journaled to andextends between the upstanding ends of side members 16 and 18 so that support link 40 depends from the shaft when the lifting arm is supporting the chair at the low position.

Any suitable means may be provided for driving lifting arm 22 to an elevated position, as for example the hydraulic piston and cylinder shown at 44, 46 respectively. Piston 44 is journaled at one end to a shaft 48 carried by upstanding central portion 20. The cylinder is attached to support link 40 and lifting arm 22 by pin 38. Thus when pressure is applied to the cylinder to force the cylinder and piston apart, pin 38 will move away from the upstanding central portion 20 through an arc, the radius of which is the length of support link 40.

Elevating mechanism also includes a parallelogram linkage which maintains the seat portion 12 of the chair horizontally oriented as lifting arm 22 pivots the chair to an elevated position. The parallelogram linkage includes an elongated link member 50 pivoted at one end 52 to knuckle 26 and pivoted at its other end to one apex of a generally triangular shaped plate 54. Another apex of plate 54 is journaled to pin 38 and the third apex is pivoted to one end of a motion control arm 56, the other end of arm 56 being journaled to shaft 36.

In operation, FIG. 1 shows elevating mechanism 10 in a low position wherein seat 12 of the dental chair is disposed adjacent a floor surface. In this position, lifting arm 22 is generally horizontally oriented and support link 40 depends from shaft 42. In order to elevate the chair, hydraulic fluid is applied to cylinder 46, by any suitable means, not shown..This tends to separate the cylinder and piston driving pin 38 upwardly in an arcuate path away from shaft 48, the are having shaft 42 as a center and the length of support link 40 as a radius. Since pin 38 is journaled to lifting arm 22, the arm is also carried upwardly, in an arcuate path. However, end 28 of the lifting arm is tied to link 32 which has as its center of rotation shaft 36. Thus, end 28 of lifting arm 22 travels in a different arcuate path than does pin 38. This causeslifting arm 22 to rotate clockwise about pin 38 as the arm is lifted. This clockwise rotation imparts a forward and downward movement to end 24 of the lifting arm. The foryvard movemement is sufficient to offset the rearward movement caused by rotation about shaft 42 so that the net result is that end 24 travels through a nearly vertical path of travel. This is illustrated in FlG. 2, wherein the location of chair seat 12 in the lowered position is shown in dotted line and its location in a fully elevated position is shown in solid line.

As the chair is elevated, arm 56 tends to rotate triangular plate 54 clockwise as shown in FIG. 2, about pin 38. This moves elongated link member 50 axially with respect to lifting arm 22 in order to maintain the seat of the dental chair horizontally oriented throughout its path of travel.

Thus, it should be appreciated that the present invention provides an elevating mechanism for dental chairs and the like in which the chair is supported on the end of a cantilevered arm and is elevated by pivoting the arm to an upright position. The present invention overcomes the drawbacks of prior art cantilevered lifts by providing a linkage arranged to move the chair laterally as it is pivoted to an upright position so that the net result is that the chair moves nearly vertically throughout its range of travel- While a hydraulic piston and cylinder has been described as the preferred drive means for elevating the chair, it should be appreciated that any other drive means such as an electric motor and drive screw can be utilized in the present invention.

Having described the invention in detail what is claim as new is:

1. An elevating mechanism for dental chairs and the like comprising:

a. a base member adapted to set on a floor surface, said base member having upstanding spaced side members;

b. a shaft journaled to and extending between said side members;

c. an elongated lifting arm having a first end adapted to support said chair forwardly of said base in cantilever fashion, and a second end;

(1. a support link havingone end keyed to said shaft and another end journaled to said lifting arm, said link supporting said arm intermediate its ends for aruate movement in a vertical plane about said shaft;

e. drive means between said base and lifting arm for driving said arm about said shaft in a vertical are, said drive means being pivotally connected to said support link at the journal of said link to said lifting arm; and

f. motion control means connected between said base and said second end operating to rotate said lifting arm in an opposite direction as said arm is driven about said fixed point so that saidv first end and the chair supported thereon, travel vertically through a substantially rectilinear path of travel.

2. A elevating mechanism for dental chairs and the like comprising: a

a. a base member adapted to set on a floor surface, said base member having upstanding spaced side members;

b. a first shaft journaled to and extending between said side members;

c. an elongated lifting arm having a first end connected to a knuckle and adapted to support said chair forwardly of said base in cantilever fashion, and asecond end;

d. a support link having one end keyed to said shaft and another end journaled to said lifting arm intermediate its end for guiding said arm through a vertical are about said shaft;

e. a second shaft journaled to and extending between said upright side members at a point below and spaced rearwardly of said first shaft;

f. a plate member supported for rotation at the journal of said support link to said lifting arm;

g. a motion control arm journaled to said second shaft and pivotally connected to said plate member;

h. an elongated link extending parallel with said lifting arm, said elongated link being pivotally connected at one end to said plate member at a point remote-from said motion control arm, said elongated link having its other end operatively connected to said knuckle whereby moving said lifting arm to an upright position causes said motion control arm to rotate said plate member to drive said elongated link axially of said lifting arm for maintaining said knuckle substantially horizontally oriented; and

i. drive means between said base and lifting arm for driving said arm about said first shaft in a vertical arc. 

1. An elevating mechanism for dental chairs and the like comprising: a. a base member adapted to set on a floor surface, said base member having upstanding spaced side members; b. a shaft journaled to and extending between said side members; c. an elongated lifting arm having a first end adapted to support said chair forwardly of said base in cantilever fashion, and a second end; d. a support link having one end keyed to said shaft and another end journaled to said lifting arm, said link supporting said arm intermediate its ends for aruate movement in a vertical plane about said shaft; e. drive means between said base and lifting arm for driving said arm about said shaft in a vertical arc, said drive means being pivotally connected to said support link at the journal of said link to said lifting arm; and f. motion control means connected between said base and said second end operating to rotate said lifting arm in an opposite direction as said arm is driven about said fixed point so that said first end and the chair supported thereon, travel verticAlly through a substantially rectilinear path of travel.
 2. A elevating mechanism for dental chairs and the like comprising: a. a base member adapted to set on a floor surface, said base member having upstanding spaced side members; b. a first shaft journaled to and extending between said side members; c. an elongated lifting arm having a first end connected to a knuckle and adapted to support said chair forwardly of said base in cantilever fashion, and a second end; d. a support link having one end keyed to said shaft and another end journaled to said lifting arm intermediate its end for guiding said arm through a vertical arc about said shaft; e. a second shaft journaled to and extending between said upright side members at a point below and spaced rearwardly of said first shaft; f. a plate member supported for rotation at the journal of said support link to said lifting arm; g. a motion control arm journaled to said second shaft and pivotally connected to said plate member; h. an elongated link extending parallel with said lifting arm, said elongated link being pivotally connected at one end to said plate member at a point remote from said motion control arm, said elongated link having its other end operatively connected to said knuckle whereby moving said lifting arm to an upright position causes said motion control arm to rotate said plate member to drive said elongated link axially of said lifting arm for maintaining said knuckle substantially horizontally oriented; and i. drive means between said base and lifting arm for driving said arm about said first shaft in a vertical arc. 